Supporters of Chicago 2016 cheer as a boat carries IOC members to the opening ceremonies of the the 121st International Olympic Committee (IOC) Session and XIII Olympic Congress at the Copenhagen Opera House in Copenhagen on Thursday.

Charles Dharapak/ Reuters

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A sand sculpture is displayed in support of holding the 2016 Olympics in Rio de Janeiro on Thursday. Rio is competing with Chicago, Madrid and Tokyo for the right to host the 2016 Summer Olympics.

Natacha Pisarenko/AP

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View of the Santiago Bernabeu stadium in Madrid on Sept. 10. Madrid is competing with Chicago, Rio and Tokyo for the right to host the 2016 Summer Olympics.

Arturo Rodriguez/AP

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In this July 11 file photo, people gather around the 60-foot tall Gundam which stands at a park in Tokyo's manmade Odaiba island, Japan. If anything can encourage busy Tokyoites to take notice of their city's bid to host the 2016 Olympics, it's a replica of the popular Japanese anime series robot, Mobile Suit Gundam, big enough to take on Godzilla.

The 1976 Olympics left Montreal with a $1 billion debt, which the province of Quebec fully paid off only in 2006. Australian taxpayers pay $32 million a year to maintain Sydney Olympic venues that now go largely unused. The projected budget for London 2012 was $3.9 billion; it's now $15.1 billion and climbing.

"It's civic pride," says Ed Hula, publisher of Around the Rings, a newsletter that follows the Olympic bid process. "It's the idea that 'we can do this' – that it's important and part of the city's history."

From pride to promotion

This notion of civic pride has often veered toward global promotion. Salt Lake City was eager to prove the falsity of stereotypes that portrayed Utah's Mormon community as insular and odd. Turin sought the Olympic spotlight to reinvent itself, saying it was more than the "Detroit of Italy" – it was an equal of Rome, Milan, or Florence. And Beijing's Olympics were nothing less than an astounding attempt to announce China's arrival as a world power.

At least two of the bid cities have had similar motivations: South America has never held an Olympics, and Chicago has always been America's so-called "second city."

Chicago's bid is unusual because of the high-profile involvement of Mayor Daley, who is "a far more powerful and engaging figure than any other person on the US Olympic Committee," says Mr. Hula.

Though President Obama and the first lady are part of an 11th-hour show of official support, Chicago's bid is most intertwined with Daley's will and legacy. "He's the only one who got the Olympics bug," Hula says. "You can't do anything in that city without his support or his involvement. He has been the person out front politically all along."

But history has proved that prestige comes with a significant cost to the public, says Jeffrey Segrave, an Olympic historian at Skidmore College in Saratoga Springs, N.Y. The economics of the Games are "extraordinarily elusive" because they involve "indirect expenses that are always difficult and cantankerous to deal with."

Some expenses can be leveraged to bring more permanent gains. Salt Lake City used the Olympics to expedite federal funding for the reconstruction and widening of a key stretch of Interstate 15.

But many expenses are largely sunk costs. Beijing spent $423 million on its national stadium but has had little use for it since. "The history and tradition of these facilities is that they lie unused and the public is paying the bill for [them]," says Mr. Segrave.

In Chicago, public opinion has fractured in the weeks leading up to the Copenhagen IOC summit. Fears about budget overruns and corruption loom, particularly in a recession. Wary Chicagoans need only look at Vancouver, British Columbia, host of February's Winter Games, to confirm their worries. The city had its credit lowered after experiencing difficulties funding its $800 million housing facility for athletes.

Windy City, cold feet

A poll conducted by the Chicago Tribune and WGN-TV in late August reported that 45 percent of Chicagoans do not want the Games in Chicago, with 47 percent supporting them. The results are a reversal of the results from February, when 64 percent wanted the Games and 28 percent did not.

Tom Tresser, a Chicago college professor, cofounded No Games Chicago, a citizen advocacy group. He is in Copenhagen to lobby the IOC against choosing his city. He cites public concerns about corruption and incompetence.

"We're trying to tell them it's very unstable here, and the people don't want this," Mr. Tresser said in the days before his departure. "The mayor has one vision to give prosperity to this city, which is building parties that are all about contracts and concrete. If it's not about high-priced stuff that we can build," he accuses Daley of reasoning, "it doesn't appear on the economic-development agenda."

Public worry over spending is "a legitimate concern," says Olympic historian David Wallechinsky. The US government does not provide federal funds to cover the Games beyond providing security, and sponsorship money is not as secure as it once was, due to the economy. That means cities can be left on shaky ground as expenses rise.

"There's no guarantee" that preliminary budgets will be right. Bidding organizations will "always tell you it's only going to cost this much, but as soon as they get the bid, it's 'Oh, we forgot this,' " says Mr. Wallechinsky. "That happens, always."

This doesn't mean that bidding for the Games is not worthwhile, Wallechinsky adds. But "a city should never bid for an Olympics thinking it will turn a profit," he says. "If they try to tell you that, it's a stab in the dark."